The present invention relates generally to bone fixation devices and more particularly to bone fixation push pins or tacks.
Bone structures in a human body, or other animals, may undergo degenerative processes which lead to weakening or an ultimate break of the bone structure. Additionally, a catastrophic event may cause a break or fracture in the bone structure. When such breaks occur, some kind of repair mechanism must generally be used to help the bone heal properly. Certain mechanisms include external fixation of the bone structure so that it can grow together in proper alignment. External fixation is fixation of the bone structure with a device placed on the outside of the derma. Other methods include internal fixation which include some mechanism placed subcutaneous to hold the bone structure in place while it heals.
Internal plate and bone fixation methods are generally known. Plates having a specific rigidity are mounted to bone structures using known fixture means. One known method of fixing a plate to a bone is using a surgical screw which is held in place through threads. These screws are inserted using a driver into a pilot hole that had been drilled into the bone. Additionally, surgical or orthopedic tacks are known to hold bone plates,in place. The tack is press fit into a pilot hole that was drilled into the bone structure. Generally, these bone tacks resemble hardware tacks. Known tacks generally included a head portion affixed to a proximal end of a tack body. The tack body has a generally sloping profile that terminates in a sharp point or relatively narrow distal end. These tacks may also include ribs that help hold the tack in place. Generally, however, the pilot hole for these tacks must be substantially equal to the greatest diameter of the tack body. If the pilot hole is not substantially equal to the width or diameter of the largest part of the tack body, great pressure must be used to insert the bone tack into the bone and hold it in place.
It is, therefore, desirable to have a bone tack that has an increased holding power without requiring the increased pressure to implant the bone tack into the bone structure. It is also desirable to decrease the resulting stress on the bone structure after implantation. When additional force is used to push a bone tack into a bone structure, greater trauma may arise than if a smaller force was used to insert a bone tack into the bone structure.
A first embodiment of the present invention includes a bone fixation tack which has a body which has a proximal end and a distal end wherein the tack is to be received in a bone structure. A head portion extends from the proximal end of the body. A removable member further extends from the head portion. Finally, a projection is operatively associated with the body portion to form a bone engaging area when implanted in the bone structure.
A second embodiment of the present invention includes a surgical fixation tack which has a tack portion having a first circumference and a proximal end and a distal end. A head portion extends from the proximal end of the tack portion. Finally, a plurality of fins extend from the tack portion and form a second circumference which is greater than the first circumference.
A third embodiment of the present invention includes a surgical tack that has a tack portion with a plurality of fins where the fins effectively reduce the surface area of the tack portion. A head portion extends from the tack portion. Finally, projections are operatively associated with the tack portion to help hold the tack portion in the structure.
The bone fixation tack according to the present invention has a generally circular interior cross section with a generally triangular total cross section. The triangular cross section provides a minimal resistance during the implantation of the bone fixation tack into a bone structure. After implantation, each point of the generally triangular cross section will provide resistance to extraction or unintended removal of the bone fixation tack from the bone structure into which it was implanted. Additionally, projections, such as barbs are formed on each of the points of the triangular cross section to also resist removal of the bone fixation tack. The head portion of the tack may also include an integrally formed insertion member which may be removed once the bone fixation tack has been affixed into the bone. Also, a plate through which the bone fixation tack will be inserted is disclosed to hold two portions of the bone relative to each other for a healing process.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.